1. Field of the Invention
The present invention relates to a planar light source device and a liquid crystal display apparatus using the same.
2. Description of Related Art
A typical liquid crystal display apparatus includes a liquid crystal display panel and a backlight unit disposed on the rear side of the panel. In this structure, heat generated by a linear light source such as a cold-cathode tube constituting the backlight unit is transferred to the liquid crystal display panel, causing nonuniform thermal distribution over the liquid crystal display panel, where uneven display is likely to occur.
One approach to overcome such drawback is to dispose a heat spreader sheet with high thermal conductivity such as aluminum on a rear surface or a side surface of a light guide plate or a linear light source constituting a backlight unit so as to uniformize the in-plane thermal distribution of a liquid crystal display panel. Such a technique is disclosed in Japanese Unexamined Patent Application Publication Nos. 09-318940 and 2001-311944, for example.
In such a structure, however, heat can be excessively deprived from a light emitting portion of the linear light source, particularly from an electrode portion. This causes the linear light source to have nonuniform thermal distribution and significantly shortens the life of the linear light source.
The present invention has been accomplished to solve the above drawbacks and an object of the present invention is thus to provide a planar light source device capable of suppressing the reduction in the life of the light source and a liquid crystal display apparatus using the same capable of suppressing the occurrence of uneven display due to heat emission by the light source.